However, the standard model for air-conditioned seats, developed by scientists at the Department of Energy's National Renewable Energy Laboratory (NREL), works like this: The fabric of the car seat is a porous mesh, so air can flow through it.
As chewing continues, the food is made softer and warmer, and the enzymes in saliva begin to break down carbohydrates in the food. After chewing, the food (now called a bolus) is swallowed. It enters the esophagus and via peristalsis continues on to the stomach, where the next step of digestion occurs.
Food enters the lungs on rare occasions, and can be dangerous, or life-threatening. The throat (pharyx). There is a flap of tissue (cartilage) called the epiglottis, its nickname is the guardian of the airways, and it closes the windpipe (trachea) when you swallow. This makes sure no food goes into the lungs. Sometimes, if people eat too fast, talk, or laugh while they are eating, the flap may not close in time and food can go down the trachea, into a bronchus, and into a lung.